1. Field of the Invention
The present invention is related to the field of materials handling technology and concerns a device for continuously gathering flat articles in a serial production of article stacks and for further processing the produced stacks.
2. Description of Related Art
In the printing and book-binding industry it is known to produce stacks of sheets, stacks of folded sheets, stacks of signatures or stacks of other printed products by providing a row of feed points, by conveying stacks being produced along the row of feed points one after the other in a substantially continuous manner and by adding one printed product to each stack at every feed point. The device for conveying the stacks being produced comprises, for example, a plurality of essentially V-shaped pockets arranged one behind the other. These pockets have upwardly-directed openings that extend substantially transverse to the conveying direction and the printed products are introduced into the pockets with one edge leading. A stack already present in the pocket is leaning against one of the walls of the pocket and, if so required, is pressed against this wall with suitable means, so that the product to be added can be introduced securely and precisely. For the same purpose, it is also possible to provide L-shaped stack supports arranged one behind the other, each respectively with a supporting surface and a foot element, wherein the supporting surfaces extend transverse to the conveying direction and advantageously are inclined relative to vertical. The supplied printed products are advantageously laid onto these supporting surfaces being guided at their leading edge, as is described, for example, in the Swiss patent application No. 2525/00 of the same applicant.
It is also known to remove the stacks of flat articles gathered in the manner briefly outlined above from the V-shaped pockets by opening the bottom of the pockets and letting the stacks fall out of the pockets driven by gravity.
In the publication EP-0908408 it is proposed to open such gathering pockets after completion of the stacks during continuous conveyance at their bottom, so that gravity relocates the stacks into lower pockets arranged to adjoin the gathering pockets. The walls of the lower pockets are movable such that the dropped stack is capable of being clamped between these walls, and so that when opening this pocket, the bottom side of the stack or all bottom edges of the flat articles gathered in the stack become freely accessible while the stack is being gripped in the lower pocket. For being bound, the exposed side of the stacks are then, for example, roughened, trimmed and/or treated with adhesive. Following this treatment, the stack is released by the pocket walls and dropped in a controlled manner.
Gathering of printed products in pockets being substantially continuously conveyed, is described also in the publication EP-0712736. Each finished stack is then clamped and gripped by the walls of the pocket such that the pocket can be opened at the bottom and the position of the stack remains unchanged relative to the pocket walls. The pocket comprises a U-shaped base part, which, for opening the pocket, is moved away downwards. The article edges on the bottom side of the stack being exposed in this manner are further treated for binding the stack, for which purpose the stack together with the clamping pocket walls is inserted into clamping tongues.
An object of the present invention is to create a device for continuously gathering flat articles into stacks and for further processing the stacks, with which device specific edges of the stacked, flat articles are aligned to one another during stacking and are made accessible for further processing on the finished stack and with which device the stacks with the exposed edge zones are conveyed to a processing operation. The device according to the invention differs from known devices with the same purpose, particularly by being more universally utilisable and simpler and by being significantly more easily adaptable to different requirements with respect to the exposure of the edge zones of the stacked, flat articles.
The device in accordance with the invention comprises, in a per se known manner, a plurality of stack supports that are substantially continuously conveyed one after the other in a conveying direction. These stack supports are essentially continuously conveyed, first, for producing the stacks by gathering articles, along a row of feed points, then through an exposure zone and from there to further processing.
The stack supports have supporting surfaces substantially aligned transverse to the conveying direction and foot elements arranged at the bottom end of each supporting surface. The foot element is actively connected to the supporting surface such that it is capable of being pressed against the supporting surface with a pressing force and such that by the action of suitable control means or by stopping the pressing force it can be spaced from the supporting surface and from this spaced position is able to be released again into the pressing position.
During the gathering operation, the flat articles are laid against the advantageously inclined supporting surfaces and their bottom edges are aligned to one another by the foot element, which in this phase is pressed against the supporting surface. The supporting surface and foot element together carry the stack in a defined position during production and after completion.
Downstream the last feed point there is an exposure zone, through which the stack supports are conveyed in substantially the same manner as along the row of feed points. Also conveyed through the exposure zone are stack support means and this in synchronism with the stack supports and aligned to them, wherein the conveying path of the stack supports and the conveying path of the stack support means are designed such that, at the entrance to the exposure zone, the stack support means are arranged immediately underneath the stack supports and such that, during conveyance through the exposure zone, they move more and more away downwards from the stack supports.
Furthermore, means for controlling the foot elements are provided in the exposure zone. A first such control means spaces the foot elements from the supporting surfaces at the point in which the stack support means are moving immediately underneath the stack supports, i.e. at the entrance of the exposure zone, such that the stacks lying against the supporting surfaces are released downwards and, still lying against the supporting surfaces, slide down onto the stack support means. The stacks are further conveyed lying against the supporting surfaces and supported by the stack support means until, as a result of the divergence of the conveying paths of stack supports and stack support means, they have slid off the stack supporting surface to such an extent that the bottom edges of the stacked flat articles protrude from the bottom edges of the supporting surfaces by a predefined value. At this point, a second control means releases the foot elements from their position spaced from the supporting surface to their pressing position. Through their sliding the stacks are now positioned between the supporting surface and the foot element, i.e. the foot element when released into the pressing position is not anymore pressed directly against the supporting surface but against the stack, so that the stack is pressed between foot element and supporting surface and, therefore, is fixed in its position relative to the supporting surface. Further sliding of the stack is not possible anymore.
With the stack clamped between the supporting surface and the foot element, the stack supports are conveyed onwards, wherein their spatial orientation can now be changed, for example, by swivelling the stack supports relative to the conveying path or by changing the direction of the conveying path. Through such changes of the spatial orientation of the stack supports and the stacks of flat articles clamped in them, the aligned edge zones protruding beyond the supporting surfaces, which were originally oriented downwards, can be oriented to suit a following processing operation.
For releasing stacked, flat articles possibly processed in the area of the exposed edge zones, from their clamped position in the stack supports, the part of the stack protruding between the supporting surface and the foot element can simply be taken hold of with suitable means and then the foot element can be brought back into its position spaced from the supporting surface.
Instead of L-shaped stack supports as described above, the device according to the invention may also comprise V-shaped gathering pockets extending substantially transverse to the conveying direction and comprising two pocket walls located opposite one another in the direction of conveyance. One of the pocket walls represents the supporting surface and the foot element closes off the distance between the pocket walls at the pocket bottom.
It goes without saying that using the device in accordance with the invention, it is not only possible to produce and further process stacks comprising a plurality of flat articles but it is also possible to clamp and further process individual articles, i.e. xe2x80x9cstacksxe2x80x9d comprising only one flat article.